Where does the expression 'the whole nine yards' come from?

Answer 1

We really do not know, though it does seem to have some relationship to the Air Force.

This may seem to support the "length of the ammunition belt", But this explanation, while tempting, doesn't work. Here are the main reasons, from the article linked below (which nicely explains what we know--and esp what we DON'T know-- about this expression). Note esp. the FIRST reason.

"First, ammunition is never measured in length of the belt. It is measured in number or rounds or in weight.

"Second, the phrase is absent from WWII literature. If it were of WWII vintage, citations of usage dating back to the 1940s would certainly have been found by now.

"Finally, the explanation itself doesn't appear until the 1990s. . . "

http://www.wordorigins.org/index.php/more/573/

Answer 2

I don't think anybody's 100% sure on the etymology of this phrase, but one of the most cited explanations refers to the length of ammuntion belts on fighter aircraft. These belts were reportedly 27 feet in length, and to unload the entire belt into an enemy plane was was to "give him the whole nine yards".

The link includes this and other possible explanations.

Answer 3

Sailing. It prefers to putting out ALL of the canvas sails to make maximum speed - to put out "the whole nine yards" of canvas sails.